Experimental evaluation of the effectiveness of the sheet pile wall breaking during vibration extraction of sheet piles

The article presents the results of evaluating the effectiveness of breaking the sheet pile wall during vibration extraction of sheet piles. There have been carried out numerous measurements of the sheet pile wall vibrations, surrounding soil massif, foundations of the adjoining structure. The observation results have shown that the overall level of dynamic impact has significantly decreased in comparison with the closed wall. The zone of propagation of vibrations along a closed wall has been determined. The results of numerical modeling are presented. Comparison of the building vibrations for the case of «non-open» and «open wall» are made. Recommendations are given on the technological sequence of sheet pile extraction.

Simple and fast prediction of train-induced track forces, ground and building vibrations

A simple and fast prediction scheme is presented for train-induced ground and building vibrations. Simple models such as (one-dimensional) transfer matrices are used for the vehicle–track–soil interaction and for the building–soil interaction. The wave propagation through layered soils is approximated by a frequency-dependent homogeneous half-space. The prediction is divided into the parts “emission” (excitation by railway traffic), “transmission” (wave propagation through the soil) and “immission” (transfer into a building). The link between the modules is made by the excitation force between emission and transmission, and by the free-field vibration between transmission and immission. All formula for the simple vehicle–track, soil and building models are given in this article. The behaviour of the models is demonstrated by typical examples, including the mitigation of train vibrations by elastic track elements, the low- and high-frequency cut-offs characteristic for layered soils, and the interacting soil, wall and floor resonances of multi-storey buildings. It is shown that the results of the simple prediction models can well represent the behaviour of the more time-consuming detailed models, the finite-element boundary-element models of the track, the wavenumber integrals for the soil and the three-dimensional finite-element models of the building. In addition, measurement examples are given for each part of the prediction, confirming that the methods provide reasonable results. As the prediction models are fast in calculation, many predictions can be done, for example to assess the environmental effect along a new railway line. The simple models have the additional advantage that the user needs to know only a minimum of parameters. So, the prediction is fast and user-friendly, but also theoretically and experimentally well-founded.